# score = 0
# score = int(input(f'请输入一个0-100的成绩:'))
# if score >= 90 :
#     print('A')
# if 80 <= score <= 89 :
#     print('B')
# if 70 <= score <= 79 :
#     print('C')
# if 60 <= score <= 69 :
#     print('D')
# if score < 60 :
#     print('E')




# i = 1
# sum = 0
# for i in range(1,101) :
#     sum += i
# print(sum)



# n = int(input("请输入一个数字:"))
# sum = 0
# for i in range(1,n+1) :
#     sum += i
# print(sum)




# num = int(input("请输入一个数:"))
# flag = True
# for i in range(2,num) :
#     if num % i ==0 :
#         flag = False
#         break
# if flag == True :
#     print(f'{num}是素数')
# else :
#     print(f'{num}不是素数')




# for num in range(2,101) :
#     flag = True
#     for i in range (2,num) :
#         if num % i == 0:
#             flag = False
#             break
#     if flag == True:
#      print(num,end=' ')




